Polyalkylene polyol esters of dialkylaminobenzoic acid and their use in photoinitiated curing processes

ABSTRACT

Amine compounds of general formula (I), ##STR1## wherein: each R 1  independently represents an alkyl group; each R 2  independently represents an alkyl group; each group X independently represents a polyalkylene polyol moiety wherein hydroxyl groups of the polyol moiety are optionally alkylated but not including a group X which includes an ethyleneoxy or di(ethyleneoxy) moiety; n and m independently represent 1, 2 or 3; and each Q is independently selected from hydrogen or halogen atoms, and alkyl, acyl, nitro, cyano, alkoxy, hydroxy, amino, alkylamino, sulphinyl, alkylsulphinyl, sulphonyl, alkylsulphonyl, sulphonate, amido, alkylamido, alkoxycarbonyl, halocarbonyl and haloalkyl groups, processes for their preparation and intermediate compounds are described. Compounds of general formula (I) are useful as radiation curing agents in polymerisation processes.

This invention relates to novel amine compounds, to their preparation,to their use as radiation curing agents in polymerisation processes, andto polymeric products cured by such amine compounds.

Amines, especially tertiary amines, are important curing agents forphotoinitiated curing processes. They are used in conjunction withphoto-excited species, commonly called photoinitiators, which react withthe amines to generate amine-derived radicals which initiatepolymerisation.

There are two commercially important aromatic amine curing agentscurrently available, ethyl-4-(N,N'-dimethylamino) benzoate (EDB) and2-n-butoxyethyl 4-(dimethylamino) benzoate (BEDB). These are highlyeffective as curing agents when used in conjunction with thioxanthoneinitiators, in particular isopropylthioxanthone (ITX). However theysuffer the disadvantage that they tend to migrate from the polymer, overtime. The surface of the polymer may be spoiled and compounds maymigrate into the substrate, which could, for example, be a food ordrinks products.

Japanese published patent application 6263814 (Toyo Ink) disclosescuring agents obtained by reacting dihydric polyol compounds, forexample ethylene glycol, with dimethylaminobenzoic acid. These are usedin curable coating compositions said to have reduced odor, and to befree from deterioration from curability. However, in experiments we havefound such curing agents to be rather slow in inducing polymerisation;and to migrate from a cured polymer at an unacceptably high rate.

It is an object of the present invention to provide an amine curingagent which is effective in inducing polymerisation and which iseffectively retained within the cured polymer. That is to say, itsmigration from the cured polymer is to be low, or nil.

In accordance with a first aspect of the present invention, there isprovided an amine compound of the general formula ##STR2## wherein: eachR¹ independently represents an alkyl group;

each R² independently represents an alkyl group;

each group X independently represents a polyalkylene polyol moietywherein hydroxyl groups of the polyol moiety are optionally alkylated;

n and m independently represent 1, 2 or 3; and

each Q is independently selected from hydrogen or halogen atoms, andalkyl, acyl, nitro, cyano, alkoxy, hydroxy, amino, alkylamino,sulphinyl, alkylsulphinyl, sulphonyl, alkylsulphonyl, sulphonate, amido,alkylamido, alkoxycarbonyl, halocarbonyl and haloalkyl groups.

Suitably, n and m independently represent 1 or 2preferably 1.

Suitably, each Q represents a hydrogen atom.

Suitably, each R¹ represents the same alkyl group.

Suitably, each R¹ represents a C₁₋₄ alkyl group, preferably methyl.

Suitably, each R² represents the same alkyl group.

Suitably, each R² represents a C₁₋₄ alkyl group, preferably methyl.

Suitably, one or each group X includes at least two etherfunctionalities.

Suitably, each X independently represents a polyalkylene glycol moiety,wherein hydroxyl groups of the moiety are optionally alkylated.

Suitably, each X represents a polyethylene glycol moiety, whereinhydroxyl groups of the moiety are optionally alkylated.

Suitably, one or preferably each, group X represents a polyol moietywhich is end-capped by an alkyl group.

Suitably, the alkyl group which end caps the group X is a C₁₋₄ alkylgroup. Preferably, it is a methyl group.

Preferably, one or preferably each group X represents a polyol moietywherein each hydroxyl group is alkylated.

Preferably, one or each group X is of the general formula --O--(CH₂--CH₂ --O)_(z) -alkyl where z has a mean value of from 2 to 20,preferably 4 to 15, most preferably 6 to 13 and the alkyl group issuitably a C₁₋₄ alkyl group, preferably methyl.

Preferably, at least one said group COX is located para to a saiddialkylamine group. Where n=m=1, preferably the group COX is locatedpara to the dialkylamine group.

In accordance with a second aspect of the present invention there isprovided a process for the preparation of a compound of general formulaI, which process comprises alkylation of a corresponding primary aminecompound (in which R₁ =R₂ =hydrogen). This may be carried out byreductive alkylation, using the appropriate alkanal.

Such a reaction can be carried out in a hydrogenator, at elevatedtemperature and pressure, and in the presence of hydrogen.

The corresponding primary amine compound can itself be prepared bysimilar hydrogenation, from the corresponding nitro compound.

The nitro compound may be easily prepared by reaction of the appropriatenitrobenzoic acid with the appropriate optionally alkylated polyolcompound retaining at least one hydroxyl group. Alternatively, theappropriate nitrobenzoic acid chloride may be employed, suitably with abase, for example an amine base, suitably triethylamine.

In accordance with a third aspect of the present invention there isprovided a process for the preparation of a compound of general formulaI, which process comprises esterification of the appropriatedialkylamine benzoyl chloride compound, with the appropriate optionallyalkylated polyol compound having at least one hydroxyl group. Thisreaction suitably takes place in the presence of a base, for example anamine base, for example triethylamine. This reaction suitably takesplace at a temperature in the range -20° C. to 40° C., preferably 0° C.to ambient temperature. The benzoyl chloride reactant may be prepared bychlorination of the corresponding benzoic acid, for example usingthionyl chloride, suitably at ambient temperature.

The invention further extends to any novel intermediates referred toherein, and to the methods for their preparation. Thus, the inventionprovides an intermediate compound of general formula ##STR3## wherein X,Q, n and m are as described in any statement herein.

The invention also extends to an intermediate compound of generalformula ##STR4## wherein X, Q, n and m are as described in any statementherein.

In accordance with a further aspect of the present invention there isprovided a polymer curing composition, which may be in kit form,comprising a compound of general formula I as described above, togetherwith a photoinitiator, the photoinitiator, when photo-excited, beingable to react with the compound of general formula I to generate anamine-derived radical.

In accordance with a further aspect of the present invention there isprovided a polymerisable composition comprising a polymerisable materialsuitably present in an amount from 80 to 97 wt. %, a compound of generalformula I, suitably present in an amount from 14 to 2 wt. %, and aphotoinitiator, suitably present in an amount from 6 to 1 wt. %.

In accordance with a further aspect of the present invention there isprovided a polymeric composition derived from said polymerisablecomposition by photo-curing.

A suitable photoinitiator may, for example, be a thioxanthone compound,preferably isopropyl thioxanthone, or an anthroquinone compound, or abenzophenone compound. Preferably, however, it is a novel benzophenoneof the type described in our co-filed patent application entitled "NovelPhotoinitiators", the contents of which are incorporated herein byreference. Thus, such a benzophenone compound is of the general formula##STR5## wherein: each Z independently represents an alkylene polyolmoiety or a polyalkylene polyol moiety, wherein hydroxyl groups of thepolyol moiety are optionally alkylated; each Y independently representsan alkylene polyol moiety or a polyalkylene polyol moiety, whereinhydroxyl groups of the polyol moiety are optionally alkylated; or analkoxy group;

each E is independently selected from hydrogen or halogen atoms andalkyl, acyl, nitro, cyano, alkoxy, hydroxy, amino, alkylamino,sulphinyl, alkylsulphinyl, sulphonyl, alkylsulphonyl, sulphonate, amido,alkylamido, alkoxycarbonyl, halocarbonyl and haloalkyl groups;

each F is independently selected from hydrogen or halogen atoms andalkyl, acyl, nitro, cyano, alkoxy, hydroxy, amino, alkylamino,sulphinyl, alkylsulphinyl, sulphonyl, alkylsulphonyl, sulphonate, amido,alkylamido, alkoxycarbonyl, halocarbonyl and haloalkyl groups;

b represents 1 to 5;

c represents 0 to 4; and

p represents 0 to 5.

Suitably, b represents 1 or 2, preferably 1.

Suitably, c represents 0 or 1, preferably 0.

Suitably, each E represents a hydrogen atom.

Suitably, p represents 0 or 1.

Suitably, each F represents a hydrogen atom.

Suitably, one or each group Z includes at least two etherfunctionalities.

Suitably, the or each group Z independently represents an alkyleneglycol or polyalkylene glycol moiety wherein hydroxyl groups of themoiety are optionally alkylated.

Suitably, the or each group Z represents an ethylene glycol orpolyethylene glycol moiety, wherein hydroxyl groups of the moiety areoptionally alkylated.

Suitably, one or preferably each, group Z represents a polyol moietywhich is end-capped by an alkyl group.

Suitably, an alkyl group which end caps the group Z is a C₁₋₄ alkylgroup. Preferably, it is a methyl group.

Suitably, one or preferably, each group Z represents a polyol moietywherein each hydroxyl group is alkylated.

Suitably, one or preferably each group Z is of the general formula--O--(CH₂ --CH₂ --O)_(e) -alkyl where e has a mean value of from 2 to20, preferably 4 to 15, most preferably 6 to 13 and the alkyl group issuitably a C₁₋₄ alkyl group, preferably methyl.

Preferably, a said group COY is located in the 2- or 4-position, mostpreferably in the 4-position.

Suitably, one or each group Y includes at least two etherfunctionalities.

Suitably, each Y independently represents an alkylene glycol orpolyalkylene glycol moiety, wherein hydroxyl groups of the moiety areoptionally alkylated.

Suitably, Y represents an ethylene glycol or polyethylene glycol moiety,wherein hydroxyl groups of the moiety are optionally alkylated.

Suitably, one or preferably each, group Y represents a polyol moietywhich is end-capped by an alkyl group.

Suitably, an alkyl group which end caps the group Y is a C₁₋₄ alkylgroup. Preferably, it is a methyl group.

Suitably, one or preferably, each group Y represents a polyol moietywherein each hydroxyl group is alkylated.

Preferably, one or preferably each group Y is of the general formula--O--(CH₂ --CH₂ --O)_(e) -alkyl where e has a mean value of from 2 to20, preferably 4 to 15, most preferably 6 to 13.

Preferably, a said group COY is located in the 2- or 4-position, mostpreferably in the 4-position.

Compounds of the general formula II, may be prepared by esterificationor transesterification of a precursor benzophenone compound to thecompound of general formula I, with the appropriate alkyl end-cappedalkylene glycol compound, having a single hydroxyl group.

When p represents 0, the preferred reaction is an esterification, usingthe appropriate benzoyl benzoic acid.

When p represents 1 and Y represents an alkylene glycol or polyalkyleneglycol moiety, end-capped by an alkyl group, the preferred reaction is atransesterification, preferably from the appropriate di(methoxycarbonyl)benzophenone compound.

When p represents 1 and Y represents an alkoxy group the favoredreaction is an esterification, using the appropriate precursor compoundhaving one ester group COY, where Y represents the alkoxy group, and onegroup --COOH.

The esterification/transesterification may be carried out under standardconditions. The esterification reaction may be carried out in an organicsolvent, for example toluene, at an elevated temperature, preferablyunder reflux, with removal of water during the reaction process.Preferably, an acid, suitably an organic acid, for example a sulphonicacid, is present. Suitably a catalyst is present. A suitable catalyst istin (II) octanoate. The transesterification reaction may be carried outin an organic solvent, for example toluene, in the substantial absenceof water, at an elevated temperature, preferably under reflux.Preferably an acid, suitably an organic acid, for example a sulphonicacid, is present. Suitably a catalyst is present, preferably an alkyltitanate.

A suitable polymerisable material is any material whose polymerisationcan be initiated by an amine radical. Preferably the polymerisation isapplied to acrylate systems where the polymerisable material (monomer)may, for example be 1,6-hexanediol diacrylate (HDDA), 2-hydroxyethylacrylate (HEA), hydroxypropyl acrylate (HPA) and methyl methacrylate(MMA).

The polymerisable materials may be suitable for surface/coating/filmapplications. They may be formulated with other components, includinginks, for printing applications.

The invention will now be further described, by way of example.

Preparation of amine curing agents of the invention

Compound 1: 2-(2-methoxyethoxy)ethyl-4-N,N'-dimethylamino benzoate

Firstly, 4-dimethylamino benzoylchloride was prepared. The reaction wasaccomplished by placing 4-dimethylamino benzoic acid (ex. Lancaster)(4.0 g, 24.22 mmol) in a 25 ml round bottom flask, to which was addedthoinyl chloride (ex. Aldrich) (3.0 ml). This reaction mixture becameorange immediately upon the addition of the thionyl chloride. Thereaction mixture was stirred for 1 hour at ambient temperature, afterwhich time the remaining thionyl chloride was removed under reducedpressure. The last trace of the thionyl chloride was removed byazeotroping with dry benzene (2×20 ml).

The brown/orange residue was then recrystallised from dry toluene (100ml). After dissolving the residue, the solution was filtered and thefiltrate dried with anhydrous sodium sulphate. It was again filtered andthe solvent removed under reduced pressure until the initial emergenceof the product. At this time the flask was removed from the rotaryevaporator and the product allowed to crystallise out naturally. Thecrystals were collected under vacuum filtration and washed with drydiethyl ether (2×20 ml). The crystals were dried under vacuum.

Data:

Yield: 3.75 g; NMR ¹ H (60 MHz, DMSO-d₆ /TMS) δ (ppm): 6.8-7.8(m,Ar,4H); 2.95 (s,Me₂ N,6H). IR (KBr ν cm⁻¹ : Note the absence of --OHgroup between 3300-3500 (C--H), 1600 (C═O), 800 (Ar). C₉ H₁₀ ONCl

Microanalysis: Requires C: 58.86% H: 5.48% N: 7.62% Found C: 58.20% H:5.54% N: 7.52%

Melting point: 136-138° C.

To a round bottom flask equipped with a 50 ml dropping funnel, was addedtriethylamine (ex. Aldrich) (1.22 g, 1.1 mol equiv.).2-(2-Methoxyethoxy)ethanol (ex. Aldrich) (1.22 g, 0.01 mol) was thenadded. The mixture was then dissolved in dry THF (20 ml). The flask wasthen placed in an ice bath and cooled to 0° C.

4-Dimethylamino benzoyl chloride (2.00 g, 0.01 mol) was also dissolvedin dry THF (20 ml). This solution was placed in the dropping funnel, andadded dropwise to the stirred, cooled solution below. After the finaladdition of the acid chloride the solution was allowed to stir for 17hours at ambient temperature. The reaction was completed by removing thetriethylamine hydrochloride by filtration, and the remaining solventunder reduced pressure. The residue that was left was redissolved inchloroform (50 ml) and washed with brine (15 ml). The organic layer wasthen removed and dried with sodium sulphate, filtered and the chloroformremoved under reduced pressure. This yielded the title compound as awhite/cream semi-solid, more solid than liquid.

Data:

Yield: 1.98 g; NMR ¹ H (100 MHz), CDCl₃ /TMS) δ (ppm): 6.6-8.0(m,Ar,4H); 4.3-4.5 (triplet,OCH₂ CH₂,2H); 3.5-3.9 (m,CH₂ --O--CH₂ CH₂--O,6H; 3.4 (s,OMe,3H); 3.0 (s,NMe₂,6H). IR (KBr) ν cm⁻¹ : 2780-3020(C--H); 1700 (C--O); 1610 (C═O); 780 (Ar) C₁₄ H₂₁ O₄ N

Microanalysis: Requires C: 62.90% H: 7.92% N: 5.24% Found C: 61.34% H:8.38% N: 5.18%

Homogeneity point: 45-50° C.

Extinction coefficient: 227700 @ 310.8 nm

Compound 2: 4-N,N'-dimethylaminobenzoyl poly(ethylene alycol)₃₅₀monomethylether

To a 25 ml round bottom flask equipped with a 50 ml dropping funnel wasadded triethylamine (ex. Aldrich) (1.22 g, 1.1 mol equiv.).Poly(ethylene glycol)₃₅₀ monomethyl ether (ex. Fluka) (3.38 g, 0.01 mol)was then added. The mixture was dissolved in dry THF (20 ml). The flaskwas then placed in an ice bath and cooled to 0° C.

4-Dimethylamino benzoyl chloride (2.00 g, 0.01 mol) was also dissolvedin dry THF (20 ml). This solution was placed in the dropping funnel, andadded dropwise to the stirred cooled solution below. After the finaladdition of the acid chloride the solution was allowed to stir for 17hours at ambient temperature.

The reaction was completed by removing the triethylamine hydrochlorideby filtration, and the remaining solvent under reduced pressure. Theresidue that was left was redissolved in chloroform (50 ml) and washedwith brine (15 ml). The organic layer was then removed and dried withsodium sulphate, filtered and the chloroform removed under reducedpressure. This yielded the title compound as a yellow/brown semi-solid,more liquid than solid.

Data

Yield: 3.21 g; NMR ¹ H (100 MHz, CDCl₃ /TMS) δ (ppm): 6.5-7.9 (m,Ar,4H);3.6 (s,PEG,manyH ˜28!; 3.3 (s,OMe,3H); 3.0 (Me₂ N--,6H). IR (KBr) ν cm⁻¹: 2800-2960 (C--H); 1700 (C--O); 1620 (C═O); 770 (Ar). C₂₄ H₄₁ O₉ N

Microanalysis: Requires C: 59.13% H: 8.42% N: 2.87% Found C: 57.81% H:8.77% N: 2.35%

Homogeneity point: 50-60° C.

Extinction coefficient: 215600 @ 310.8 nm

Compound 3: 4-N,N'-dimethylaminobenzoyl Poly(ethylene glycol)₃₅₀monomethylether

Compound 4: 4-N,N'-dimethylaminobenzoyl Poly(ethylene glycol)₇₅₀monomethylether

Compounds 3 and 4 were synthesised using a similar method to each other,as follows.

Esterification of 4-nitrobenzoic acid

The following reactants were placed in a 500 ml three necked roundbottom flask equipped with a thermometer, overhead stirrer, and a DeanStark apparatus with a condenser.

4-Nitrobenzoic acid (ex. Lancaster) (50.0 mg, 0.3 mol)/(56.0 g, 0.33mol)

Poly(ethylene glycol)₅₅₀ monomethyl ether (ex. Fluka) (181.0 g, 0.30mol)

Poly(ethylene glycol)₇₅₀ monomethyl ether (ex. Fluka) (250.0 g, 0.33mol)

Sulphuric acid 96% (2.60 g, 0.03 mol)/(3.4 g 0.035 mol) t-BAB (0.5g)/(0.54 g) Toluene (100.0 ml)

The reaction mixtures were then heated to reflux while stirring. Theheating was continued until all the water produced in the reactions hadbeen azeotroped out by the toluene, (expected amount 6 ml, actual amount5.8 ml). This took 5.5 hours, after which time the solutions were cooledand lime (CaCO₃ ˜10 g) was added to neutralise the sulphuric acid andany excess 4-nitrobenzoic acid. The solutions were filtered underreduced pressure and the solvent removed under reduced pressure. Thisgave rise to a semi-solid brown product in both cases.

Hydrogenation of the nitro compounds

These reactions took place in a hydrogenator. 100 g of the respectivePEG compound was dissolved in methanol (500 ml). Raney Nickel (TradeMark) catalysts (10 g, 50% with water) were suspended in methanol (100ml). To these were added 5 drops of acetic acid to ensure that the pHwas at about 5.5.

The two solutions were then placed in the hydrogenator. This wasmaintained at 26° C. under 3 atmospheres of hydrogen and stirred at 600rpm. After 16 hours the solutions were removed and the Raney Nickelcatalysts were removed by filtration using a filter bed, under vacuum.The compounds were analysed using HPLC.

Reductive alkylation

The orange/yellow filtrates from the above reactions were again placedin the hydrogenator, along with the Raney Nickel catalyst (10 g, 50%with water) and para formaldehyde (10 g). The reaction mixtures weremaintained at 50° C. under 3 atmospheres of hydrogen and stirred at 600rpm for 72 hours. The solutions were then removed, filtered using thefilter bed to remove all the catalyst and the solvents removed underreduced pressure. This yielded, in the case of the PEG 550, anorange/yellow semi-solid, and in the case of PEG 750, a waxy solid.

Data on Compound 3

Yield: 193.75 g; NMR ¹ H (100 MHz, CDCl₃ /TMS) δ (ppm); 6.4-7.8(m,Ar,4H); 3.6 (s,PEG,manyH ˜48!); 3.0 (s,NMe₂,6H). IR (KBr) ν cm⁻¹ :2700-3000 (C--H); 1700 (C--O); 1610 (C═O); 770 (Ar). C₃₄ H₆₁ O₁₄ N

Microanalysis: Requires C: 57.70% H: 8.62% N: 1.98% Found C: 54.97% H:9.18% N: 1.39%

Homogeneity point: 50-55° C.

Extinction coefficient: 171300 @ 310.0 nm

Data on Compound 4

Yield: 263.56 g; NMR ¹ H (100 MHz, CDCl₃ /TMS) δ (ppm); 6.5-7.8(m,Ar,4H); 3.7 (s,PEG,manyH ˜64!); 3.4 (s,OMe,3H); 3.0 (s,NMe₂.,6H). IR(KBr) ν cm⁻¹ : 2700-3000 (C--H); 1700 (C--O); 1600 (C═O); 780 (Ar). C₄₂H₇₇ O₁₈ N

Microanalysis: Requires C: 57.08% H: 8.72% N: 1.58% Found C: 54.53% H:9.63% N: 1.57%

Extinction coefficient: 127300 @ 296.1 nm

Comparison compounds

Compound C1: Ethyl dimethylamino benzoate

This is a commercially available product and for the tests describedbelow was obtained from Lambson Fine Chemicals Limited of Castleford.

Compound C2: 2-n-Butoxyethyl 4-(dimethylamino) benzoate

This is a commercially available product and for the tests describedbelow was obtained from Lambson Fine Chemicals Limited of Castleford.

Compound C3: Ethylene glycol di(4-methylaminobenzoate)

The above compound was synthesised by placing ethylene glycol (ex.Fisons) (0.169 g, 2.723 mmol) in a 100 ml round bottom flask. To thiswas added triethylamine (ex. Aldrich) (1.216 g, 2.2 mol equiv.) and THF(30 ml). Diethylamino benzoyl chloride (1.0 g, 5.446 mmol) was dissolvedin dry THF (20 ml) and placed in a dropping funnel. The acid chloridewas added dropwise to the cooled, stirred solution of ethylene glycoland triethylamine. After the last addition the solution was left for 17hours, stirring at ambient temperature. The reaction was completed byremoving the triethylamine hydrochloride by filtration from thesolution. The remaining filtrate was then evaporated to dryness underreduced pressure. The residue was then dissolved in chloroform (50 ml)and the product washed with water (2×20 ml). The chloroform extract wasthen dried with anhydrous sodium sulphate, filtered and the chloroformremoved under reduced pressure, to give a pale cream crystallineproduct.

Yield: 1.37 g; NMR ¹ H (270 MHz, CDCl₃ /TMS) δ (ppm): 6.4-7.9 (m,Ar,8H);4.5 (s,--CH₂ CH₂ --, 4H); 2.8 (s,2Me₂ N--,12H). IR (KBr) ν cm⁻¹ :2800-2960 (C--H); 1690 (C--O); 1610 (C═O); 760 (Ar) C₂₀ H₂₄ O₄ N₂

Microanalysis: Requires C: 67.37% H: 6.78% N: 7.61% Found C: 66.17% H:6.71% N: 7.40%

Melting point: 171-174° C.

Compound C4: Poly(ethylene glycol)₃₀₀ di(4-dimethylamino benzoate)

Compound C5: Poly(ethylene glycol)₆₀₀ di(4-dimethylamine benzoate)

The preparation of the compounds C4 and C5 was afforded using the samemethod given for compounds 3 and 4 above.

Esterification of 4-nitrobenzoic acid

The following reactants were placed in a 500 ml round bottom flaskequipped with a thermometer, overhead stirrer and a Dean Stark apparatusequipped with a condenser.

4-Nitrobenzoic acid (50.07 g, 0.3 mol, apx. 1/3 mole)/(100 g, 0.6 mol,apx. 1/3 mole)

Poly(ethylene glycol)₃₀₀ (49.40 g, 0.16 mol) /poly(ethylene glycol)₆₀₀(200 g, 0.33 mol) t-BAB (0.5 g)/(0.5 g)

Sulphuric acid 96% (4.0 g, 0.04 mol) /4.4 g, 0.045 mol)

The respective mixtures were then stirred and azeotropically distilledto remove the water and form the respective esters (expected amount 12ml, actual amount 11.8 ml). This took approximately 6 hours, after whichtime the solutions were cooled and lime added (CaCO₃ ˜10 g) toneutralise the sulphuric acid and any remaining 4-nitrobenzoic acid thatremained. The solutions were filtered and the solvent removed underreduced pressure.

Hydrogenation of nitro compounds

These reactions were carried out using a hydrogenator. The respectivePEG compounds (100 g) were dissolved in methanol (500 ml). Raney Nickelcatalysts (10 g, 50% with water) were suspended in methanol (100 ml). Tothese were added 5 drops of acetic acid to ensure that the pH was atabout 5.5.

The two solutions were than placed in a hydrogenator. This wasmaintained at 20° C., under 3 atmospheres of hydrogen and stirred at 600rpm. After 16 hours the solutions were removed and the Raney Nickelcatalyst removed by filtration, using a filter bed under reducedpressure. The compounds were analysed using HPLC.

Reductive alkylation

The filtrates from the above reactions, suspended in methanol (100 ml),were placed in the hydrogenator, along with some more Raney Nickelcatalyst (10 g, 50% with water) and para formaldehyde (10 g). Thehydrogenator was maintained at 50° C., under 3 atmospheres of hydrogenand stirred at 600 rpm for 72 hours. The solutions were then removed,filtered using the filter bed to remove all the catalyst and thesolvents removed under reduced pressure. This yielded, in bothinstances, an orange viscous liquid.

Data on Compound C4

Yield: 80.4 g; NMR ¹ H (10 MHz, CDCl₃ /TMS) δ (ppm); 6.4-8.2 (m,Ar,8H);3.7 (s,PEG,manyH ˜28!); 3.1 (s,NMe₂.,12H). IR (KBr) ν cm⁻¹ : 2800-3000(C--H); 1700 (C--O); 1610 (C═O); 770 (Ar). C₃₂ H₄₈ O₁₀ N₂

Microanalysis: Requires C: 61.93% H: 7.74% N: 4.52% Found C: 59.89% H:8.02% N: 3.97%

Extinction coefficient: 276600 @ 308.7 nm

Data on Compound C5

Yield: 235.84 g; NMR ¹ H (100 MHz, CDCl₃ /TMS) δ (ppm); 6.6-8.1(m,Ar,8H); 3.7 (s,PEG,manyH ˜56!); 3.1 (s,NMe₂.,12H). IR (KBr) ν cm⁻¹ :2800-3000 (C--H); 1700 (C--O); 1600 (C═O); 770 (Ar). C₄₆ H₇₆ O₁₇ N₂

Microanalysis: Required C: 59.48% H: 8.19% N: 3.02% Found C: 57.37% H:8.84% N: 2.82%

Extinction coefficient: 285200 @ 302.9 nm

Novel benzophenone initiators

As described below, isopropyl thioxanthone (ITX) was the photoinitiatorused in most of the tests. However, also used were novel PEG-modifiedbenzophenone photoinitiators, prepared as follows.

Compound A: 4-Benzoylbenzoyl poly(ethylene glycol)₃₅₀ monomethylether

2.1 g of poly(ethylene glycol)₃₅₀ mono methyl ether, 1 g of4-benzoylbenzoic acid and 1 g of p-toluene sulphonic acid were refluxedwith 100 ml of toluene until all water present had been driven over.Catalytic amounts of tin (II) octanoate were added and the mixturerefluxed for 10 hours. After removal of the toluene, washing with sodiumcarbonate (to neutralise any free acid present) and drying under vacuum,a brown liquid was obtained (which became extremely viscous onstanding). The product structure was confirmed by 100 MHz proton NMR.

Compound B: Di- poly(ethylene glycol)₃₅₀ monomethylether!benzophenone-4.4'-dicarboxylate

The first step was to prepare 4,4¹ -dimethyl benzophenone. To do this,25 ml of p-toluoyl chloride was added slowly to a stirred mixture of 30g of anhydrous aluminium trichloride and 115 ml of dry toluene. Theresulting solution was ref luxed for 6 hours before the product wasisolated by addition of the reaction solution to a solution of 200 mlwater and 100 ml conc. HCl. The resulting red solid was distilled (shortpath) at 141° C. at 4 mm Hg. The distillate solidified on cooling to awhite solid.

Melting point:=90-92° C.;

Elemental analysis: C₁₅ H₁₄ O;

requires % C=85.68, H=6.71;

found % C=85.66, H=6.44;

100 MHz proton NMR: solvent=CD₂ Cl₂ ; aromatic protons 7-8 ppm AA¹ BB¹system (8H); methyl protons 2.4 ppm (6H).

The 4,4¹ -dimethyl benzophenone was then oxidised to the correspondingdicarboxylic acid. A solution of glacial acetic acid and the 4,4¹-dimethyl benzophenone was added to a solution of aq. acetic acid (80%v/v) and chromium trioxide and stirred at ambient temperature for 24hours. The addition of water facilitated a pale green precipitate.Isolation and H¹ NMR/elemental analysis showed partial oxidation. Thereaction was driven to completion by refluxing, at 65° C., for 24 hours.

Elemental analysis: C₁₅ H₁₀ O₅

requires % C=66.67, H=3.74

found % C=66.71H=3.65

60 MHz H¹ NMR aromatic protons exhibiting an AA¹ BB¹ splitting system8-8.5 ppm.

% Yield=67.43%

FTIR exhibited a large --OH stretch (persisted after drying product invacuum oven at 40° C. for 48 hours).

The dicarboxylic acid compound was esterified to form the dimethylester. The esterification was achieved by refluxing in methanol and anacid for 24 hours. The crude product was taken into THF and washed withwater to remove free acid. Recrystallisation was from dry ethanol.Characterisation was by H¹ NMR which gave the AA¹ BB¹ aromatic splittingpattern (8.20-8.70 ppm) and a singlet assigned to the methyl protons(4.20 ppm). Integration was in the ratio 4:3. FTIR exhibited no --OHstretch after drying.

Elemental analysis:

requires % C=68.45, H=4.73

found % C=68.67, H=4.54

Finally, the dimethyl ester was transesterified to form the titlecompound. 2.5 g Dimethyl ester, 6.25 g poly(ethylene glycol)₃₅₀monomethylether and 50 ml of dry toluene was refluxed in a Dean andStark apparatus for 1 hour. 0.25 g of Tilcom Trade Mark--Ti(OPr)₂ (OBu)₂! was injected and refluxing at 100° C. was continued for 4 hours. Themethanol side product was removed using a fractionating column and thereaction was driven to completion by refluxing for a further 2.5 hours.Removal of the catalyst was achieved by addition of 2 ml of water to thevigorously stirred, cooled solution and filtration of the resultingprecipitate of titanium oxide. The surplus water was removed byreturning the toluene solution back to the Dean and Stark apparatus for1 hour. Removal of the solvent produced a viscous, light brown liquid(yield c. 2 g).

Analysis:

60 MHz H¹ NMR; methyl ether 3.45 ppm singlet (6H) ethylene protons 3.75ppm singlet (˜58H) aromatic protons 7.95-8.50 ppm AA¹ BB¹ (8H) HPLC;flow rate 1 ml/min, 254 nm, 20 micro liter sample loop, a 50/50acetonitrile water mobile phase. The resulting trace showed two distinctgroups of peaks, attributed to the mono and di-substituted PEG esters.

Note on microanalysis

It has been noted that the microanalysis (CHN) results on all compoundscontaining polyethylene glycol (PEG) are not as accurate as desired.This is not due to impurities in the compounds, but to the fact that PEGcompounds contain average chain lengths. For example, a PEG compound ofaverage molecular weight 350 contains chains that vary in between 2 and12 ethylene glycol units. In order to calculate the percentage of carbonand hydrogen present in the chain it was necessary to determine theaverage number of units present. The method of calculating this is shownbelow.

PEG chain=350

Repeating unit (--OCH₂ CH₂ O--)=44.053

Mono methyl ether (OMe)=31.034

350-31.034=318.966

318.966 divided by 44.053=7.24

=˜7 repeating units

Therefore, one can assess the number of carbon, hydrogen and oxygenatoms in the chain and it is also possible to calculate the overallnumber of individual carbon, hydrogen and oxygen atoms and hence theoverall percentage composition. ##STR6##

Effectiveness of Compounds as Curing Agents

For the purpose of these tests, unless otherwise stated, the standardpre-polymer mixture was as follows:

1-6 hexanediol acrylate (monomer): 93 wt %

amine curing agent: 5 wt %

isopropyl thioxanthone (ITX-photoinitiator): 2 wt %.

It was found that all of the compounds 1-4 and comparison compoundsC1-C5 above, dissolved into such a prepolymer mixture, except forcomparison compound C1, which could not therefore be studied, and iswithout utility, at least in relation to the prepolymer mixture used forthese tests.

Curing was by a medium pressure UV lamp. The results presented belowrelate firstly to the determination of whether the polymer cures and ifso, how quickly; and, secondly, to the propensity of the amines tomigrate from a polymer film after curing. The two methods employed toaddress these aspects were Real Time Infra Red (RT-IR) and High PressureLiquid Chromography (HPLC).

Methods of Data Acquisition

RT-IR analysis of the rate of cure of each of the pre Polymer mixtures

The use if RT-IR allows the rate of cure of each of the samples to beanalysed. This method allows an infra-red spectrum to be taken, then afrequency is chosen, one at which the transmittance would change duringpolymerisation. Commonly used is the acrylate stretch at 810 cm⁻¹, theacrylate double bonds disappearing during curing. Using the time drivefacility, it allows infra-red analysis while the sample is beingirradiated with a medium pressure UV lamp, thus allowing the increase intransmittance to be monitored. This gives an indication of the rate ofpolymerisation. A second spectrum was run. This showed the finalposition of the acrylate stretch.

Two RT-IR's were run on each pre-polymer mixture. The samples wereprepared as follows. A drop of each pre-polymer mixture was placedbetween two polyethylene sheets in the center of a polyether spacer of25 μm. This was to ensure that all the films were of the same thickness.This sandwiched sample was then placed between two NaCl plates, which inturn were placed in a holder unit. This entire unit was then placed intothe infra-red machine and the spectrum run.

HPLC method used for analysing the Propensity of the amines to migrate

The method for testing the propensity of the amines to migrate was thesame throughout.

The migratable amine content of each film was analysed as follows.Initially a drop of the pre-polymer mixture was placed on a piece ofsatinised paper. This was then evenly spread over the surface using a"K" bar which gave a film thickness of between 50-60 μm.

For each of the curing agents, samples of film were taken after:

i) No passes of the Colordry unit (i.e., the UV lamp)

ii) 2 passes of the Colordry unit.

iii) 4 passes of the Colordry lamp.

iv) 6 passes of the Colordry lamp.

The Colordry unit contains a medium pressure mercury lamp. The samplesare placed on a moving belt (in these trials this was set at 24meters/minute). It was important to ensure two main factors during thisstage of the trial. Firstly, that all the samples taken, of satinisedpaper and film, were of the same size. It was for this reason that ametal template was made that gave samples of 21×28 mm. Secondly, thatthe curing of the film was as unaffected by oxygen inhibition aspossible. This was ensured by placing the paper and uncured film in acell with a quartz window. This cell was then evacuated with nitrogenand sealed. Only then was the sample passed through the Colordry unit.

The 21×28 mm samples of each pre-polymer mixture at 0, 2, 4 and 6 passeswere then placed in individual 7 ml sample vials. To each vial was added5 ml of a de-gassed acetonitrile/water 50/50 mix, enough to immerse eachsample. The vials were then placed in a dark cupboard for 20 hours.After this time the vials were removed and the sample extracted fromeach vial. All that was left in each vial was the solvent containing themigratables that had leached out from the film in the 20 hour period.

Methods of Data Analysis

RT-IR analysis of the rate of cure of each of the ore polymer mixtures

For each sample three spectra were run, to allow an average to be taken.Each spectrum had a decay curve which represents the rate ofpolymerisation. The steeper the gradient of the curve, the faster therate. The angle of the gradient was measured and this could then be usedto compare the rate of polymerisation achieved by the different curingagents.

HPLC method used for analysing the migration of amines from films

These samples were then prepared for HPLC analysis by filtering each oneusing Sartorus Millistart 0.45 μm disposable filters. This was to ensurethat there were no solid contaminants that would damage the HPLC column.

Chromographs of the amine components for each of the films were runprior to the trials. This was to ensure that firstly the elution timewas known and, secondly, to determine whether the respective aminecomponents had any characteristic shaped peaks.

After filtration each sample was injected on to the HPLC column. Eachsample was run in acetonitrile/water 50/50 mixture. The data from eachrun was then used to analyse the migratable content of each film.

On the chromatogram for the solution containing migrated aminecompounds, the area under each of the relevant peaks was noted.

It was assumed that the contents of the solution that had contained thefilm that had not passed the UV lamp, contained 100% migratable aminecompound, because the pre-polymer mixture was not irradiated. The valuesfor the areas under the peaks from the solutions that had containedfilms that had passed the UV lamp, 2, 4 and 6times could then becorrelated respectively to the 100% migration value of the uncuredsolution.

Results

                  TABLE 1    ______________________________________    RT-IR Trials    Compound      RT-IR Data    ______________________________________    1             67°    2             75°    3             74°    4             19°    C1            56°    C2            52°    C3            inoperable    C4            50°    C5            18°    ______________________________________

The angles of gradient expressed are a measure of the decay curve whichrepresents the rate of polymerisation. The steeper the gradient, thefaster the rate of polymerisation.

                  TABLE 2    ______________________________________    HPLC Migration Analysis               % Amine Compounds    Compound     0      2          4   6    ______________________________________    1            100    27         25  12    2            100     0          0   0    3            100    12          0   0    4            100    73         56  21    C1           100    42         41  25    C2           100    67         54  25    C3           inoperable    C4           100    42         20  15    C5           100    38         18  13    ______________________________________

It will be seen that by the use of preferred amines of the presentinvention, improved properties can be achieved, in terms of migration ofthe amines from the cured polymer, with the improvement being mostmarked for compounds 2 and 3indicating a preferred mean molecular weightthe PEG component of the -OPEGOMe chain, of around, 250-650. curing timeis also very fast using compounds 1, 2 and 3although slower for compound4. Comparison between compounds 2 and C4and between compounds 3 and C5,are of interest because of the closeness of the mean molecular weightsof the PEG components between these pairs of compounds. The propertiesof compounds 2 and 3 are, surprisingly, significantly better than thoseof C4 and C5 respectively, both in terms of cure rate, and migrationcharacteristics.

Further tests

Several curing agents were tested further, to assess their efficiency inpolymerising HDDA. This was assessed using FTIR as described above.

Curing Agent 5%, photoinitiator 2%, HDDA 93%

a) Ethyl-4-dimethylamino benzoate EDB!/Compound A/HDDA

b) Compound 2/Compound A/HDDA

c) Compound 2/Compound B/HDDA

Results

Percentage transmittance at 810 cm⁻¹

    ______________________________________    No. of UV    passes      0      2          4    6    ______________________________________    a            7.79  61.74      63.42                                       60.97    b           13.06  60.24      65.63                                       60.23    c           12.48  53.43      59.83                                       70.15    ______________________________________

It will be seen that the novel PEG-substituted initiators and curingagent provide good rates of reaction and high degrees of polymerisation,in addition to the good or excellent self-migration properties, shown bythe other tests. The PEG-substituted initiators and PEG-substitutedcuring agent were fully compatible in the formulation.

The use of the amine curing agents of the type of compounds 1 to 4 canbe expected to offer certain further advantages. Firstly, the use of theend-capped glycol can be expected to have a plasticizing effect, usefulto increase the flexibility, and hence the durability, of films.Secondly, its incorporation may be expected to increase thecompatibility of the amine compounds, with paper surfaces. When polymerfilms, cured using amine compounds, are used in conjunction with paper,the extra adherence is desirable. Thirdly, the compounds are likely tobe highly soluble in water, such that the amine curing agents could beused in conjunction with aqueous curing formulations. These advantagesare likely to be furthered, when the novel benzophenone initiators arealso used.

The reader's attention is directed to all papers and documents which arefiled concurrently with or previous to this specification in connectionwith this application and which are open to public inspection with thisspecification, and the contents of all such papers and documents areincorporated herein by reference.

All of the features disclosed in this specification (including anyaccompanying claims, abstract and drawings), and/or all of the steps ofany method or process so disclosed, may be combined in any combination,except combinations where at least some of such features and/or stepsare mutually exclusive.

Each feature disclosed in this specification (including any accompanyingclaims, abstract and drawings), may be replaced by alternative featuresserving the same, equivalent or similar purpose, unless expressly statedotherwise. Thus, unless expressly stated otherwise, each featuredisclosed is one example only of a generic series of equivalent orsimilar features.

The invention is not restricted to the details of the foregoingembodiment(s). The invention extends to any novel one, or any novelcombination, of the features disclosed in this specification (includingany accompanying claims, abstract and drawings), or to any novel one, orany novel combination, of the steps of any method or process sodisclosed.

We claim:
 1. An amine compound of the General formula ##STR7## wherein:each R¹ independently represents an alkyl group;each R² independentlyrepresents an alkyl group; each group X independently represents apolyalkylene polyol moiety wherein hydroxyl groups of the polyol moietyare optionally alkylated but not including a group X which includes anethyleneoxy or di(ethyleneoxy) moiety; n and m independently represent1, 2 or 3; and each Q is independently selected from hydrogen or halogenatoms, and alkyl, acyl, nitro, cyano, alkoxy, hydroxy,amino, alkylamino,sulphinyl, alkylsulphinyl, sulphonyl, alkylsulphonyl, sulphonate, amido,alkylamido, alkoxycarbonyl, halocarbonyl and haloalkyl groups.
 2. Acompound according to claim 1, wherein n and m represent
 1. 3. Acompound according to claim 1, wherein each Q represents a hydrogenatom.
 4. A compound according to claim 1, wherein each R¹ represents aC₁₋₄ alkyl group.
 5. A compound according to claim 1, wherein each R²represents a C₁₋₄ alkyl group.
 6. A compound according to claim 1,wherein one or each group X represents a polyol moiety which isend-capped by an alkyl group.
 7. A compound according to claim 1 whereinone or each group X is of the general formula --O--(CH₂ --CH₂ --O)_(z)-alkyl where z has a mean value of from 6 to 13 and the alkyl group is aC₁₋₄ alkyl group.
 8. A compound according to claim 1, wherein group Xexcluding any optional alkyl group has a molecular weight in the range250-750.
 9. A compound according to claim 1, wherein group X excludingany optional alkyl group has a molecular weight in the range 250-650.10. A process for the preparation of a compound of general formula Iaccording to claim 1, which process comprises alkylation of acorresponding primary amine compound.
 11. A process for the preparationof a compound of general formula I according to claim 1, which processcomprises esterification of the appropriate dialkylamine benzoylchloride compound, with the appropriate optionally alkylated polyolcompound having at least one hydroxyl group.
 12. A polymer curingcomposition comprising a compound of general formula I as described inclaim 1, together with a photoinitiator, the photoinitiator, whenphoto-excited, being able to react with the compound of general formulaI to generate an amine-derived radical.
 13. A polymerisable compositioncomprising a polymerisable material, a compound of general formula I asdescribed in claim 1 and a photoinitiator.
 14. A polymeric compositionderived from said polymerisable composition of claim 13 by photo-curing.15. A method of polymerising a polymerisable material, the methodcomprisingcombining a polymerisable material, a compound of generalformula I as described in claim 1 and a photoinitiator to produce apolymerisable composition; and photo-curing the polymerisablecomposition to produce a polymeric composition,wherein the polymericcomposition is produced at a rate of polymerisation, measured using RealTime Infra Red analysis, which is greater using the compound of generalformula I as described in claim 1 than using a first comparativecompound of formula I wherein n and m each represent 1, R¹ and R² eachrepresent a methyl group, Q represents a hydrogen atom and X representsa methoxy end-capped polyethylene glycol-750 moiety.
 16. A method ofpolymerising a polymerisable material, the method comprisingcombining apolymerisable material, a compound of general formula I as described inclaim 1 and a photoinitiator to produce a polymerisable composition; andphoto-curing the polymerisable composition to produce a polymericcomposition,wherein the polymeric composition has an amine migrationrate, measured using High Pressure Liquid Chromatography analysis, whichis less using the compound of general formula I as described in claim 1than using a first comparative compound of formula I wherein n and meach represent 1, R¹ and R² each represent a methyl group, Q representsa hydrogen atom and X represents a methoxy end-capped polyethyleneglycol-750 moiety.
 17. The method according to claim 15, wherein thepolymeric composition has an amine migration rate, measured using HighPressure Liquid Chromatography analysis, which is greater using thecompound of general formula I than using the first comparative compoundof formula I.
 18. The method according to claim 15, wherein thepolymeric composition is produced at a rate of polymerisation, measuredusing Real Time Infra Red analysis, which is greater using the compoundof general formula I than using a second comparative compound of formulaI wherein n and m each represent 1, R¹ and R² each represent a methylgroup, Q represents a hydrogen atom and X represents --OCH₂ OCH₂ OMe,and/or the polymeric composition has an amine migration rate, measuredusing High Pressure Liquid Chromatography analysis, which is less usingthe compound of general formula I than using the second comparativecompound of formula I.
 19. The method according to claim 16, wherein thepolymeric composition is produced at a rate of polymerisation, measuredusing Real Time Infra Red analysis, which is greater using the compoundof general formula I than using a second comparative compound of formulaI wherein n and m each represent 1, R¹ and R² each represent a methylgroup, Q represents a hydrogen atom and X represents --OCH₂ OCH₂ OMe,and/or the polymeric composition has an amine migration rate, measuredusing High Pressure Liquid Chromatography analysis, which is less usingthe compound of general formula I than using the second comparativecompound of formula I.
 20. The method according to claim 17, wherein thepolymeric composition is produced at a rate of polymerisation, measuredusing Real Time Infra Red analysis, which is greater using the compoundof general formula I than using a second comparative compound of formulaI wherein n and m each represent 1, R¹ and R² each represent a methylgroup, Q represents a hydrogen atom and X represents --OCH₂ OCH₂ OMe,and/or the polymeric composition has an amine migration rate, measuredusing High Pressure Liquid Chromatography analysis, which is less usingthe compound of general formula I than using the second comparativecompound of formula I.